The constitutive production of colony stimulating factor 1 by invasive human breast cancer cells.

Colony Stimulating Factor 1 (CSF-1) and its receptor, the c-fms proto-oncogene product, are expressed in normal and malignant tissues. The many actions of CSF-1 include induction of urokinase-type plasminogen activator (uPA), a serine protease involved in extracellular matrix degradation. To explore the role of CSF-1 in breast cancer progression, we evaluated the expression of CSF-1, c fms, and uPA in human breast cancer cell lines well-characterized for differing degrees of invasive, metastatic capability. The more invasive cell lines expressed elevated levels of CSF-1 by Northern analysis and ELISA. Increased uPA expression was noted in these same cell lines. CSF-1 receptor mRNA transcripts and protein were demonstrable in the different cell lines. These data suggest a role for CSF-1 in the autocrine and paracrine regulation of tumor progression in breast cancer.